The present invention relates to materials for organic electroluminescence devices which are used as a light source such as a planar light emitting member of televisions and a back light of displays, exhibit high efficiency of light emission and have excellent heat resistance and a long life, organic electroluminescence devices using the materials, novel compounds and processes for producing materials for electroluminescence devices.
Electroluminescence (EL) devices using organic compounds are expected to be used for inexpensive full color display devices of the solid light emission type which can display a large area and development thereof has been actively conducted. In general, an EL device is constituted with a light emitting layer and a pair of electrodes faced to each other at both sides of the light emitting layer. When a voltage is applied between the electrodes, electrons are injected at the side of the cathode and holes are injected at the side of the anode. The electrons are combined with the holes in the light emitting layer and an excited state is formed. When the excited state returns to the normal state, the energy is emitted as light.
Heretofore, organic EL devices require higher driving voltages and show inferior luminance of emitted light and inferior efficiencies of light emission in comparison with inorganic devices. Moreover, properties of organic EL devices deteriorate very rapidly. Therefore, heretofore, organic EL devices have not been used practically. Although the properties of organic EL devices have been improved, organic EL devices exhibiting a sufficient efficiency of light emission and having sufficient heat resistance and life have not been obtained. For example, a phenylanthracene derivative which can be used for EL devices is disclosed in Japanese Patent Application Laid-Open No. Heisei 8(1996)-12600. However, an organic EL device using this compound exhibited an efficiency of light emission as low as about 2 to 4 cd/A and improvement in the efficiency is desired. In Japanese Patent Application Laid-Open No. Heisei 8(1996)-199162, an EL device having a light emitting layer containing a fluorescent dopant of a derivative of an amine or a diamine is disclosed. However, this EL device has a life as short as 700 hours at an initial luminance of emitted light of 300 cd/m2 although the efficiency of light emission is 4 to 6 dc/A and improvement in the life is desired. In Japanese Patent Application Laid-Open No. Heisei 9(1997)-268284, a material for EL devices having phenylanthracene group is disclosed. This material exhibits a marked decrease in the luminance of emitted light when the material is used at a high temperature for a long time and heat resistance is insufficient. Moreover, these devices do not emit light in the region of orange to red color. Since emission of red color is indispensable for the full color display by an EL device, a device emitting light in the region of orange to red color is desired. When these materials are used as the host material and other compounds are used as the doping material, a long life cannot be obtained. It is necessary for practical use that an initial luminance of emitted light of 10,000 d/m2 or greater be exhibited. However, this value has not been achieved. In Japanese Patent Application Laid-Open No. Heisei 11(1999)-152253, an example is disclosed in which a material for organic EL devices having a binaphthalene structure is added to a light emitting layer having the property to transfer electrons such as a layer of an aluminum complex or the like. However, in this example, the aluminum complex or the like emits light and the material for organic EL devices does not function as the light emitting center since the energy gap of the light emitting layer of the aluminum complex or the like is smaller than the energy gap of the material for organic EL devices.
Synthesis of arylamines used as a material for organic EL devices has been conducted by the Ullmann reaction using an amine and an iodobenzene. It is described, for example, in Chem. Lett., pp. 1145 to 1148, 1989; the specification of U.S. Pat. No. 4,764,625; and Japanese Patent Application Laid-Open No. Heisei 8(1996)-48974 that a triarylamine is produced by the reaction of a corresponding iodobenzene and a diarylamine in an inert hydrocarbon solvent such as decaline at 150xc2x0 C. or higher in the presence of one equivalent or more of copper powder and a base such as potassium hydroxide as the typical example.
However, the process using the Ullmann reaction has drawbacks in that an expensive iodide must be used as the reacting agent, that the reaction cannot be applied to many types of compounds, that the yield of the reaction is not sufficient, that the reaction requires a temperature as high as 150xc2x0 C. and a long time and that waste liquid containing a great amount of copper is formed since copper powder is used in a great amount and environmental problems arise.
The present invention has been made to overcome the above problems and has an object to provide a material for organic electroluminescence devices, an organic electroluminescence device and a novel compound which exhibit high efficiency of light emission and have a long life and excellent heat resistance and a process for producing the material for organic electroluminescence devices.
As the result of extensive studies by the present inventors to develop the material for organic EL devices having the advantageous properties described above and an organic EL device using the material, it was found that the object can be achieved by using the compounds represented by general formulae [1] and [3] to [10] which are shown below. The present invention has been completed based on this knowledge.
It was also found by the present inventors that the above object can be achieved by using the compounds represented by general formulae [11] and [11xe2x80x2] as the doping material or the light emitting center.
It was further found by the present inventors that a tertiary arylamine which is a material for organic EL devices can be synthesized with a high activity by the reaction of an amine and an aryl halide in the presence of a catalyst comprising a phosphine compound and a palladium compound and a base. The present invention has been completed based on the above knowledge.
The material for organic electroluminescence devices (referred to as the material for organic EL devices) of the present invention is a compound represented by following general formula [1]: 
wherein A represents a substituted or unsubstituted arylene group having 22 to 60 carbon atoms, X1 to X4 each independently represent a substituted or unsubstituted arylene group having 6 to 30 carbon atoms, X1 and X2 may be bonded to each other, X3 and X4 may be bonded to each other, Y1 to Y4 each independently represent an organic group represented by general formula [2], a to d each represent an integer of 0 to 2 and, when the arylene group represented by A has 26 or less carbon atoms, a+b+c+d greater than 0 and the arylene group does not contain two or more anthracene nuclei; general formula [2] being: 
wherein R1 to R4 each independently represent hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms or cyano group or form a triple bond by a linkage of R1 and R2 or R3 and R4, Z represents a substituted or unsubstituted aryl group having 6 to 20 carbon atoms and n represents 0 or 1.
The material for organic electroluminescence devices of the present invention may also be a compound represented by following general formula [3]: 
wherein B represents a substituted or unsubstituted arylene group having 6 to 60 carbon atoms, X1 to X4 each independently represent a substituted or unsubstituted arylene group having 6 to 30 carbon atoms, X1 and X2 may be bonded to each other, X3 and X4 may be bonded to each other, Y1 to Y4 each independently represent an organic group represented by general formula [2] described above, a to d each represent an integer of 0 to 2 and at least one of groups represented by B, X1, X2, X3 and X4 has a chrysene nucleus.
It is preferable that general formula [3] means following general formula [4], general formula [5] or general formula [6]. 
wherein X1 to X4, Y1 to Y4 and a to d are each independently the same as those in general formula [3]. 
wherein B, X1, X2, Y1, Y2, a and b are each independently the same as those in general formula [3]. 
wherein B, X1, X2, Y1, Y2, a and b are each independently the same as those in general formula [3].
The material for organic electroluminescence devices of the present invention may also be a compound represented by following general formula [7]: 
wherein D represents a divalent group having a tetracene nucleus or a pentacene nucleus, X1 to X4 each independently represent a substituted or unsubstituted arylene group containing 6 to 30 carbon atoms, X1 and X2 may be bonded to each other, X3 and X4 may be bonded to each other, Y1 to Y4 each independently represent an organic group represented by general formula [2] described above and a to d each represent an integer of 0 to 2.
It is preferable that general formula [7] means following general formula [8]: 
wherein X1 to X4, Y1 to Y4 and a to d are each independently the same as those in general formula [7], R51 to R60 each independently represent hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms or cyano group and adjacent groups among the groups represented by R51 to R60 may be bonded to each other to form a saturated or unsaturated and substituted or unsubstituted carbon ring.
The material for organic electroluminescence devices of the present invention may also be a compound represented by following general formula [9]: 
wherein E represents a divalent group comprising an anthracene nucleus which is substituted with aryl groups or unsubstituted, X5 to X8 each independently represent a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, X5 and X6 may be bonded to each other, X7 and X8 may be bonded to each other, Y1 to Y4 each independently represent an organic group represented by general formula [2], a to d each represent an integer of 0 to 2, and when the group represented by E is an unsubstituted group: 
at least two of X5 to X8 contains a substituted or unsubstituted group: 
The material for organic electroluminescence devices of the present invention may also be a compound represented by following general formula [10]: 
wherein Ar1 and Ar3 each independently represents a divalent group selected from a group consisting of substituted and unsubstituted phenylene groups, substituted and unsubstituted 1,3-naphthalene groups, substituted and unsubstituted 1,8-naphthalene groups, substituted and unsubstituted fluorene groups and substituted and unsubstituted biphenyl groups, Ar2 represents a divalent group selected from a group consisting of substituted and unsubstituted anthracene nuclei, substituted and unsubstituted pyrene nuclei, substituted and unsubstituted phenanthrene nuclei, substituted and unsubstituted chrysene nuclei, substituted and unsubstituted pentacene nuclei, substituted and unsubstituted naphthacene nuclei and substituted and unsubstituted fluorene nuclei, X5 to X8 each independently represent a substituted or unsubstituted arylene group having 6 to 20 carbon atoms, X5 and X6 may be bonded to each other, X7 and X8 may be bonded to each other, Y1 to Y4 each independently represent an organic group represented by general formula [2] described above, a to d each represent an integer of 0 to 2, a+b+c+dxe2x89xa62, e represents 0 or 1, f represents 1 or 2 and, when Ar2 represents an anthracene nucleus, a case in which a=b=c=d and AR1 and Ar3 both represent p-phenylene group is excluded.
The material for organic electroluminescence devices of the present invention may also be a compound represented by following general formula [11]: 
wherein F represents a substituted or unsubstituted arylene group having 6 to 21 carbon atoms, X1 to X4 each independently represent a substituted or unsubstituted arylene group having 6 to 30 carbon atoms, X1 and X2 may be bonded to each other, X3 and X4 may be bonded to each other, Y1 to Y4 each independently represent an organic group represented by general formula [2] described above, a to d each represent an integer of 0 to 2, and a+b+c+d greater than 0.
It is preferable that the group represented by F in general formula [11] is a group represented by following general formula [12], general formula [13] or general formula [14]: 
wherein R5xe2x80x2 to R24xe2x80x2 each independently represent hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms or cyano group and adjacent groups among the groups represented by R5xe2x80x2 to R24xe2x80x2 my be bonded to each other to form a saturated or unsaturated carbon ring; 
wherein R25xe2x80x2 to R34xe2x80x2 each independently represent hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms or cyano group and adjacent groups among the groups represented by R5xe2x80x2 to R24xe2x80x2 my be bonded to each other to form a saturated or unsaturated carbon ring.
The material for organic EL devices of the present invention which is represented by any of general formulae [1], [3] to [11] and [11xe2x80x2] can be used also as the light emitting material for organic electroluminescence devices.
The organic electroluminescence (EL) device of the present invention comprises a light emitting layer or a plurality of thin films of organic compounds comprising a light emitting layer disposed between a pair of electrodes, wherein at least one of the thin films of organic compounds is a layer comprising a materials for organic EL devices represented by any of general formulae [1], [3] to [11] and [11xe2x80x2].
It is preferable that, in the above organic EL device, a layer comprising the material for organic EL devices represented by any of general formulae [1], [3] to [11] and [11xe2x80x2] as at least one material selected from a group consisting of a hole injecting material, a hole transporting material and a doping material is disposed between the pair of electrodes It is preferable that, in the above organic EL device, the light emitting layer comprises 0.1 to 20% by weight of a material for organic EL devices represented by any of general formulae [1], [3] to [11] and [11xe2x80x2].
It is preferable that, in the above organic electroluminescence device, one or more materials selected from a group consisting of a hole injecting material, a hole transporting material and a doping material each independently comprise 0.1 to 20% by weight of the material for organic EL devices represented by any of general formulae [1], [3] to [11] and [11xe2x80x2].
It is preferable that, in the above organic EL device, the light emitting layer is a layer comprising a stilbene derivative and a material for organic EL devices represented by any of general formulae [1], [3] to [11] and [11xe2x80x2].
In the above organic EL device, a layer comprising an aromatic tertiary amine derivative and/or a phthalocyanine derivative is disposed between a light emitting layer and an anode.
It is preferable that, in the above organic EL device, the energy gap of the material for organic electroluminescence devices represented by general formula [11] is smaller than the energy gap of a host material by 0.07 eV or greater.
The novel compound of the present invention is represented by following general formula [11xe2x80x2]: 
wherein F represents a group represented by general formula [14], X1 to X4 each independently represent a substituted or unsubstituted arylene group having 6 to 30 carbon atoms, X1 and X2 may be bonded to each other, X3 and X4 may be bonded to each other, Y1 to Y4 each independently represent an organic group represented by general formula [2] described above, a to d represent each an integer of 0 to 2, and a+b+c+d greater than 0; general formula [14] being: 
wherein R25xe2x80x2 to R34xe2x80x2 each independently represent hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms or cyano group and adjacent groups among the groups represented by R5xe2x80x2 to R24xe2x80x2 my be bonded to each other to form a saturated or unsaturated carbon ring.
The process for producing a material for organic EL devices of the present invention comprises reacting, in a presence of a catalyst comprising a phosphine compound and a palladium compound and a base, a primary amine or a secondary amine represented by following general formula [15]:
R(NRxe2x80x2H)kxe2x80x83xe2x80x83[15]
wherein k represents an integer of 1 to 3; when k represents 1, R and Rxe2x80x2 represent hydrogen atom, an alkyl group or a substituted or unsubstituted aryl group; and when k represents 2 or 3, R represents an alkylene group or substituted or unsubstituted arylene group and Rxe2x80x2 represents hydrogen atom, an alkyl group or a substituted or unsubstituted aryl group, with an aryl halide represented by following general formula [16]:
Ar(X)mxe2x80x83xe2x80x83[16]
wherein Ar represents a substituted or unsubstituted aryl group, X represents F, Cl, Br or I and m represents an integer of 1 to 3, and producing a material for organic electroluminescence devices comprising an arylamine compound.
It is preferable that the arylamine described above is a compound represented by following general formula [17]: 
wherein F represents a substituted or unsubstituted arylene group having 6 to 60 carbon atoms, X1 to X4 each independently represent a substituted or unsubstituted arylene group having 6 to 30 carbon atoms, X1 and X2 may be bonded to each other, X3 and X4 may be bonded to each other, Y1 to Y4 each independently represent an organic group represented by general formula [2] described above, a to d each represent an integer of 0 to 2, and a+b+c+d greater than 0.
It is preferable that the phosphine compound is a trialkylphosphine compound, a triarylphosphine compound or a diphosphine compound.